It is known in the art to use capping devices for applying threaded caps to pre-threaded containers. Such devices utilize a clutch to control the amount of torque applied to the cap so that the container is properly closed but prevents too much torque from being applied that could strip the threads of the container and the cap. Also, it is desired to prevent the over tightening of the cap.
This has been accomplished by using rings of concentric magnets with some form of control to control the axial position of the magnets. Various devices have also incorporated rings of magnets of alternating polarity. Even though such devices have been available, they have tended to be complex and costly, and not very reliable with regard to retaining a pre-set torque, and thus many capping devices utilizing spring loaded mechanical and friction clutches are still in use but a need still exists for a device incorporating a reliable and simplified but effective clutch mechanism.
One prior art device can be found in U.S. Pat. No. 5,197,258, issued Mar. 30, 1993 to Johanek in which a clutch is adapted for use in a capping device to apply a pre-selected amount of torque to the driven component having a pair of axially aligned circular cylinders of equal diameter each having a generally smooth engaging surface facing the other clutch cylinder. Each of the cylinders has cavities in the rear side for containing magnets. The magnets are secured in the cavities by means of a cured polymeric resin. The maximum torque provided by the clutch is controlled by using removable spacer disks of varying thicknesses and having a diameter equal to that of the cylinder positioned between the engaging surfaces.
The device disclosed in U.S. Pat. No. 5,437,139, issued on Aug. 1, 1995 to Martin deals with a cylindrical magnet ring in the body of the head surrounding a cap chuck driving element in a low friction bearing in the head, each having an array of permanent magnets, distributed around the periphery. The chuck-driving element rotates with the magnet ring until the resistance of a cap being threaded on the container exceeds a predetermined torque limit, after which the magnet ring rotates relative to the stationary chuck-driving element. The spring for urging the chuck downward is fully contained within the head.
Yet another device is that found in U.S. Pat. No. 5,809,742, that issued on Sep. 22, 1998 to Takakusaki, et al in which a plurality of permanent magnets are embedded around the entire outer periphery at the upper end of a spindle with adjacent permanent magnets presenting magnetic poles of different polarities. As the capping head moves through a threadable engaging zone, co action between the permanent magnets causes the capping head to rotate clockwise causing a cap to be threadably engaged with a container.
U.S. Pat. No. 5,714,820, that issued on Feb. 3, 1998 to Mitsuhashi, et al deals with magnetic coupling that includes a cylindrical housing, a spindle, an adjusting plate, two pairs of permanent magnet discs, two hysteresis material discs, and a screw member.
The spindle is rotatably supported at its axial position by the housing. The adjusting plate is rotatably supported by the spindle to partition as interior of the housing into two sections in a direction of the spindle. The two pairs of permanent magnets are provided in the two corresponding section to respectively oppose each other. One of each pair of permanent magnet discs is fixed in the housing and the other thereof is fixed to the adjusting plate. Each permanent magnet disc has magnetic poles with polarities that alternate in a circumferential direction. The hysteresis material discs are fixed to the spindle and arranged between the corresponding pairs of permanent magnet discs at a predetermined gap. The screw member fixes the adjusting plate to the housing. When the adjusting plate is released and pivoted, the mutual positional relationships between the respective opposing magnetic poles of the two pairs of permanent magnet discs are adjusted simultaneously.
U.S. Pat. No. 6,240,678 that issued Jun. 5, 2001 to Spether deals with a capping head assembly that has a first housing with a spindle-mounting collar and supports a clutch housing. The clutch housing has an upper portion with a first magnetic ring and a lower portion with a second magnetic ring. The lower portion is freely rotatable relative to the upper portion and permits the adjustment of the air gap between the first and second magnetic rings. A locking mechanism maintains the adjusted air gap at a selected value that represents a definable torque level in the magnetic clutch. The capping head also includes a post assembly calibration system that establishes a known reference point that compensates for manufacturing tolerances between individual capping heads.
There is disclosed in U.S. Pat. No. 5,490,369 that issued Feb. 13, 1996, to Ellis, a capping head with magnetic clutch that includes a housing assembly including a magnetic clutch interconnecting a drive spindle and a quill for applying a closure to a container. The magnetic clutch consists of opposed rings of magnets and one of the rings is disposed in a piston ring assembly that is quick and easily adjustable relative to the other to vary the torque limit of the clutch. A simple yet efficient clamping assembly is employed to facilitate ready adjustment and retention of the movable piston ring.
There is shown in an Arol Company brochure, not dated, a synchronous magnetic type of head. This device differs from the device herein by the use of straight sided ball bearings as the contact thrust bearing, but more importantly, it uses a synchronous magnetic type of head as opposed to the hysteresis type of head as used in the inventive device herein.
Basically, the synchronous clutch utilizes two discs with multiple magnets that are set up to oppose each other. To rotate one of the discs relative to the other disc you must overcome the magnetic attraction from the north pole to the south pole. The torque is a pulsating torque from zero to maximum. The number of magnets located around the disc will determine how many pulsations there will be in one revolution. To change peak torque levels in this type of design you need to adjust the air gap between the magnets. Larger air gaps provide for smaller peak torques.
U.S. Pat. No. 7,181,892, that issued on Feb. 27, 2007 to the inventors herein deals with a capping head with a magnetic clutch that is useful for applying pre-threaded closures onto threaded containers with improved sensitivity. The device allows for the adjustment of the torque that is required for capping containers such that variable sized and variable types of containers can be capped.
In the instant invention, essential construction and attributes of the devices that are disclosed in the aforementioned '892 patent are also a part of this devices herein, and in addition, the devices of the instant invention are constructed such that they can be cleaned using spray washing without the water affecting any part of the device.
In addition, the construction of the instant devices is such that the liquids that are contained in the containers to be capped do not affect the devices of this invention when they splash and wash over the equipment that is used to cap the containers.
In addition to the novel cup assemblies that cover the devices, this invention teaches the correct sealing that is needed to provide unaffected devices and further, discloses an inventive method of greasing the components without having to disassemble the devices.
None of the devices disclosed in the prior art have the advantages of the devices of the instant invention. None of the devices disclosed in the prior art have the simplicity and novel means of adjusting the torque in the magnetic clutch assembly as does the device of the instant invention. In addition, the devices of this invention have the advantages of preventing contamination by water and other liquids during the filling and capping of liquid containers, and further, have the capability of being greased without having to disassemble the device. In addition, the improvements on the inventive devices can be accomplished without changing the capability of being able to read the adjustment scales on the outside surface of the magnetic clutch assembly, nor the adjustment scales on the outside surface of the upper spring assembly for adjusting the tension in the spring, that are novel features of these devices.